The present invention refers to a pipe switch or multiport valve, in particular to a two-way pipe switch such as a two-way multiport valve for regulating a flow of bulk material between one inlet and two outlets.
The German patent No. 35 02 818 describes a two-way pipe switch for bulk material which has a housing with an inlet port connectable to a coaxial first outlet port via a first flow path and to a second outlet port via a second flow path which branches off rectangularly from the first flow path. Accommodated in the housing is a cock which regulates the flow from the inlet port to the outlet ports and includes two spaced lateral circular disks connected by a cross piece at a level so as to allow to block one outlet port when the cock is in one end position and to block the other outlet port when the cock occupies the other end position. Such a pipe switch allows the supply of granulated or pulverulent bulk material to a silo arranged below the second outlet port by turning the cock by 90.degree. from the first end position to the second end position. Thus, the cross piece of the cock extends perpendicular to the first flow path and acts as baffle plate. Such a rectangular deflection of the flow of bulk material in the second position of the cock results in a considerable pressure drop. Further, the cock can be reversed or controlled only after cleaning the conduit in order to be free of bulk material. Such cleaning is necessary because when shutting off the conveying, particles of bulk material still present in the conduit can penetrate during changing of the cock at least from the second end position to the first end position into the gap between the cross piece at its end face facing away from the bulk material flow and the area of the inner housing wall between the first and second outlet port so that eventually the rotation of the cock will be blocked.
A further drawback of the two-way pipe switch according to DE-PS No. 35 02 818 resides in the fact that upon changing the cock from the first end position into the second end position during continuous flow of bulk material, particles penetrate into the gap between the respective end face of the cross piece and the area of the inner housing wall between the inlet port and the first outlet port.